The Fourth Unforgivable

Disclaimer: The characters and places present in this story were created by J.K. Rowling.

A/N: Huge thankyou to Gaia30 (Linz) who beta-ed/omega-ed this.

After the match, the common room was filled with Gryffindor cheer. While Fred and George lifted Angelina onto their shoulders, Harry sneaked out with Ron and Hermione so that they could talk about the previous night and find their bags.

As they walked down a corridor that he thought he'd seen before, Harry told them about Snape and Gilbert and what they had missed while asleep. Then he remembered the bookmark. He pulled it from his pocket. "This fell out of the book, but I don't think they noticed." Hermione took it from him and looked closely at it. It was all black, with an unrecognizable emblem at the top.

"What do you think the symbol stands for?" asked Ron.

"I'm not sure. I can find out, though. I just need some time to research it," Hermione replied. She turned to Harry. "What did Snape say about the boy?"

"He said it wasn't good employing 'their kind'-" Harry started.

"I knew it! He isn't human," Ron announced triumphantly.

"What? What makes you think that? Maybe Snape just meant child labour or something," said Hermione.

Ron snorted. "I've heard Percy drone on and on about it. Loads of vampires work for upper-class families now. Keeping themselves safe from all the vampire-hunters while getting some money to buy blood. I bet he's been playing the messenger between Snape and what's-his-name."

"Gilbert," supplied Harry.

"Yeah," said Ron, seeming pleased with his theory.

"I suppose it makes sense," said Hermione, looking at the finger the boy had bitten. "I just wish we knew what book it was and why that man - Gilbert - was so nervous about handing it over. It might have something to do with that potion Snape was making, like instructions on how to brew it."

Harry had almost forgotten the hullabaloo over the "love potion". It still puzzled him. The trio rounded a corner and discovered their bags lying abandoned on the floor.

"We could try and find the secret room again," suggested Harry, wishing he still had the Marauder's Map, and wondering if the room was charted on it.

"Nah, we have to go to rehearsal. I don't think we'd find it again, anyway," said Ron. Hermione and Ron departed hastily, to avoid angering Fleur. Harry thought about searching for the secret room alone, but reasoned that it would be too easy to get lost in the labyrinth of Hogwarts.

Harry was walking back to the common room, rubbing the sore spot on his shoulder where the Bludger had hit him, when he was interrupted by a voice.

"Just the boy I was looking for!"

Harry spun round to see a man walking towards him. The man was smiling as though they knew each other, but Harry couldn't tell if he recognized him or "the famous Harry Potter".

He must have noticed the curiosity in Harry's expression, because he promptly introduced himself. "Mundungus Fletcher," he said, shaking Harry's hand violently. The light picked up the silver strands of hair that framed his face, making him seem slightly ethereal. The effect was ruined, though, by the smell of whisky on his breath. "I'm here to see Dumbledore on official business, but your godfather wanted me to give you this," he said, handing over a letter.

"Oh, er, thanks. How do you know S- my godfather?" asked Harry. He couldn't help noticing the letter also smelled faintly of Ogden's Old Firewhiskey.

"We go back to before your time," Fletcher replied, still grinning. "But maybe I'll tell you someday. For now, just think of us as old acquaintances." He grabbed Harry's hand for one last shake, then walked off towards Dumbledore's office. Harry looked at the envelope, saw his name in Sirius' familiar messy scrawl, and found it hard to doubt Fletcher's sincerity.

Harry rushed back to the Gryffindor Tower, eager to read Sirius' letter. It had been a long time since he had last received one from Sirius, and whenever Harry tried owling him, Hedwig came back days later, still clutching his letter, despite having always managed to deliver the letters before. The boys' dorm was empty when Harry arrived. He guessed that the other fifth-years were either eating an early lunch or getting started on homework. He opened the letter and began to read.

Dear Harry,

The job Dumbledore gave me is taking longer than I expected, but I should be back before Christmas. I just wanted to write to say be careful. There's been an attack on a well known wizard family. It looks like it was just a raid, because no one was hurt, and the Ministry has done a good job of keeping it quiet, but people are starting to believe that Voldemort is back. It's important that as many as possible are prepared before his next move. Keep your guard up, Harry.

Sirius

P.S. Remus says hello.

Harry sat down on the edge of his bed. An attack. It was weird thinking about Voldemort directly after so many months of pushing those thoughts to the back of his mind. Harry had almost forgotten him, but was now acutely aware of everything going on outside school.

He wondered if the Death Eaters had attacked under cover of night, or arrogantly disregarded the possibility of a counterattack and raided during the day. And did they send up the Dark Mark? He tried to picture the scene, and with complete clarity saw a grand house sitting alone in the country. The door was kicked in, and through the windows he could see flames licking at the expensive furniture, and cloaked figures rummaging around desks, searching for something. The Dark Mark glistened menacingly above the house.

There was a sudden, sharp knock at the door. Harry jumped slightly as he heard someone calling inside. He stuffed the letter inside his robes as the door flew open.

"Harry! Fancy finding you here," said George, with an I'm-planning-something smile.

"What do you want?" asked Harry suspiciously, moving closer. Fred, George and Lee stepped just inside the door.

"How are you, Harry? Feeling okay?" said Fred, ignoring him.

"Oh, I'm fine." He waited a few seconds. "What do you want?"

"There's no point keeping it from you; we do want something. Really, we should've come straight out with it because nothing gets past you, Harry. You really can't teach that kind of perception," Fred sighed.

"We came to you because we knew you were someone we could count on," said Lee. "Because we needed something only you have. Because we caught some Slytherins snooping around the Gryffindor changing rooms. Great game, by the way."

"Spies, Harry. Filthy spies trying to beat us at Quidditch by learning our plays. Unfortunately, we were a bit late catching them. They saw a lot, Harry, and we're going to have to rethink our entire strategy," said George earnestly.

"It wouldn't be fair on us if they had an advantage, so we have to even things out. If they resort to such underhanded tactics, we have no choice but to follow suit."

"Ah. But I don't see how I can help," replied Harry. The only way he could think of was by lending them his Invisibility Cloak, but how could they possibly know about that?

"Something of ours that you still have," said Fred, exasperated. Harry felt really dense. He was definitely missing something. He raised an eyebrow.

"The eye, Harry, the eye we kept on Ginny for Mum," said George. Suddenly, Harry remembered the floating eyeball the twins had charmed to follow Ginny around school. Harry opened his trunk and pulled out a jar of scarab beetles.

"Our Speyeball. I t's been a long time since we last saw her," said Fred with a sigh.

"Er, Speyeball?" said Harry, staring at the floating mess.

"Yeah, that's what we call it. This is just a prototype, but it'll do. We've charmed it so it follows who you tell it to. It should help us find out some things about the Slytherins' game plans," said Lee.

"Only, Angelina's bound to find out if we use it, so we were wondering if you could instead?" said George.

"Well, I-"

"Great! Everything the eye sees comes up on this piece of parchment, and we've been working like house-elves to get sound, too. We thought we might need an ear, but the Speyeball can cope with both sound and vision. All you have to do is tap it with your wand and say, 'Show me', and then the person's name, and the Speyeball will find and follow them."

"When you want it to stop, just say, 'Sleep' and tap the parchment again," added Lee.

"We'll be back in a few days to pick it up. You can tell us what you saw then," said George.

"Thanks, mate," said Fred, clapping Harry on the shoulder.

Harry was so preoccupied with the disgusting mass that was the Speyeball that he didn't realise they were leaving until the door slammed. Something tells me that this is the sort of thing I'm going to regret later. But they'll be back soon, so I'd better get to it. For a moment he considered the immorality of spying on an opponent, but the memories of all the dirty tricks Slytherin employed during Quidditch hushed his conscience. He pulled out his wand. Wait...who am I supposed to be spying on, exactly? Finally, still with some uncertainty in his tone, he said, "Show me the Slytherin spy."

The Speyeball rose. It floated up and moved slowly towards the door. Harry rushed to open it, and watched the Speyeball as it glided down the staircase. He picked up the piece of parchment and followed the Speyeball's progress through the school. It was slightly fascinating, seeing and hearing parts of the school when he wasn't actually there. Hermione's on her way back from the library... There's Parvati and Lavender giggling over Witch Weekly... Oh, Professor Binns must have walked through a student again... If he concentrated really hard on the parchment, everything around him seemed to dissolve and it was as though he were walking around Hogwarts, hearing the groan of its doors and seeing the crumbling walls, not as a relayed sensation, but for real.

After a while, Harry wondered where the Speyeball was going. He recognised the path it was taking, because he'd walked it so many times, but the Speyeball wasn't edging its way towards the Slytherins as it was meant to; it was going to Dumbledore's office. As it approached two goblin statues, Snape appeared on the piece of parchment. All at once the Speyeball's path made sense. In retrospect, "Slytherin spy" did seem a little ambiguous.

Harry was about to shout, "Sleep!", but what would the Speyeball do? Hover in mid-air in that same spot, where any professor could find it before Harry retrieved it? That's no good. I don't want anyone to know I'm behind this. And Fred, George, and Lee could get in trouble as well. Maybe I should just let it keep going... Might as well keep watching. I don't have anything else to do. Besides homework.

The Speyeball stayed in the shadows most of the time. Harry guessed that it was charmed that way. He tried absently to imagine how the twins had got hold of an eyeball, but the prospects seemed gruesome. Harry dismissed most of his ideas. Surely he would have noticed if Malfoy had lost an eye.

The Speyeball hovered over Snape's shoulder as he walked into Dumbledore's office. It looked like Dumbledore was having a meeting. Harry felt guilty about eavesdropping on Dumbledore. He also felt certain that at any moment, one of the wizards would spot the Speyeball. But they all seemed preoccupied, and were mid-discussion when Snape entered. Mundungus Fletcher stood opposite Dumbledore.

"Severus, has it been confirmed?" launched Mundungus, not bothering with pleasantries.

"I am afraid so," replied Snape, less crisply than Harry expected.

"Then we have no time to waste. If you still want me to take over for her, Albus, I'll have to start straight away," said Mundungus.

"Yes, I still think that would be best. Severus, do you have any idea if the potion will work on him when he is not at full strength?" asked Dumbledore. Harry sat up, listening hard at the mention of a potion. Work on who?

"I see no reason why it shouldn't."

"Good, then Mundungus can replace her and keep control over him until then," said Dumbledore. His mood seemed to change slightly; he seemed happier for a moment, but his face soon resumed its solemnity. "We must be prepared for the May 20th attack, even if it means resorting to somewhat drastic measures."

Mundungus nodded in assent and moved toward the door. To Harry's surprise, the Speyeball followed Mundungus out, instead of staying with Snape. Harry's stomach dropped. What's going on? Why is the Speyeball following Mundungus Fletcher? He's a Slytherin spy? Are the charms broken? Harry didn't know how the Speyeball identified people; maybe it had made a mistake. But Harry was getting used to a pattern with strangers: trust, then truth, damage, and pain.

He took Sirius's letter from his robes and stared at it. What if this isn't really from Sirius? How can I know for sure? He looked for clues in the wording, the handwriting, and nearly crumpled it up in frustration. There were so many different things swirling about in his mind. The potion, the overheard conversations, the "vampire" boy, Voldemort's attack, the mystery book -- and now, as if he didn't already have enough to ponder, Mundungus's loyalty. Maybe Dumbledore has the right idea, with that Pensieve. I've got a few thoughts I wouldn't mind getting rid of. It would leave him the space he needed to concentrate on important things, like Quidditch, and not looking like a prat in front of Cho. Then there was the terrifying prospect of OWLs at the end of year. Whispers of practice exams had nearly given Ron a heart attack.

Finally Harry came to a decision, something solid he could rely on. He would wait until Ron and Hermione came back and then tell them everything. He turned back to the parchment lying on his bed and took out his wand.

"Sleep."